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Oracle数据库诊断案例-redo log日志组处于高激活状态

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本文主要是关于Oracle数据库诊断案例-redo log日志组处于高激活状态情况下的办法。

作者：eygle 来源：CSDN 2008年2月2日

平台:SunOS 5.8 Generic_108528-23 sun4u sparc SUNW,Ultra-Enterprise
数据库:8.1.5.0.0
症状:响应缓慢，应用请求已经无法返回
登陆数据库,发现redo日志组除current外都处于active状态

oracle:/oracle/oracle8>sqlplus "/ as sysdba"SQL*Plus: Release 8.1.5.0.0 - Production on Thu Jun 23 18:56:06 2005(c) Copyright 1999 Oracle Corporation.  All rights reserved.Connected to:Oracle8i Enterprise Edition Release 8.1.5.0.0 - ProductionWith the Partitioning and Java optionsPL/SQL Release 8.1.5.0.0 - ProductionSQL> select * from v$log;    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------         1          1     520403   31457280          1 NO  ACTIVE              1.3861E+10 23-JUN-05         2          1     520404   31457280          1 NO  ACTIVE              1.3861E+10 23-JUN-05         3          1     520405   31457280          1 NO  ACTIVE              1.3861E+10 23-JUN-05         4          1     520406   31457280          1 NO  CURRENT             1.3861E+10 23-JUN-05         5          1     520398   31457280          1 NO  ACTIVE              1.3860E+10 23-JUN-05         6          1     520399   31457280          1 NO  ACTIVE              1.3860E+10 23-JUN-05         7          1     520400  104857600          1 NO  ACTIVE              1.3860E+10 23-JUN-05         8          1     520401  104857600          1 NO  ACTIVE              1.3860E+10 23-JUN-05         9          1     520402  104857600          1 NO  ACTIVE              1.3861E+10 23-JUN-059 rows selected.SQL> /    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------         1          1     520403   31457280          1 NO  ACTIVE              1.3861E+10 23-JUN-05         2          1     520404   31457280          1 NO  ACTIVE              1.3861E+10 23-JUN-05         3          1     520405   31457280          1 NO  ACTIVE              1.3861E+10 23-JUN-05         4          1     520406   31457280          1 NO  CURRENT             1.3861E+10 23-JUN-05         5          1     520398   31457280          1 NO  ACTIVE              1.3860E+10 23-JUN-05         6          1     520399   31457280          1 NO  ACTIVE              1.3860E+10 23-JUN-05         7          1     520400  104857600          1 NO  ACTIVE              1.3860E+10 23-JUN-05         8          1     520401  104857600          1 NO  ACTIVE              1.3860E+10 23-JUN-05         9          1     520402  104857600          1 NO  ACTIVE              1.3861E+10 23-JUN-059 rows selected.

如果日志都处于active状态，那么显然DBWR的写已经无法跟上log switch触发的检查点。

接下来让我们检查一下DBWR的繁忙程度:

SQL> !oracle:/oracle/oracle8>ps -ef|grep ora_  oracle  2273     1  0   Mar 31 ?       57:40 ora_smon_hysms02  oracle  2266     1  0   Mar 31 ?       811:42 ora_dbw0_hysms02  oracle  2264     1 16   Mar 31 ?       16999:57 ora_pmon_hysms02  oracle  2268     1  0   Mar 31 ?       1649:07 ora_lgwr_hysms02  oracle  2279     1  0   Mar 31 ?        8:09 ora_snp1_hysms02  oracle  2281     1  0   Mar 31 ?        4:22 ora_snp2_hysms02  oracle  2285     1  0   Mar 31 ?        9:40 ora_snp4_hysms02  oracle  2271     1  0   Mar 31 ?       15:57 ora_ckpt_hysms02  oracle  2283     1  0   Mar 31 ?        5:37 ora_snp3_hysms02  oracle  2277     1  0   Mar 31 ?        5:58 ora_snp0_hysms02  oracle  2289     1  0   Mar 31 ?        0:00 ora_d000_hysms02  oracle  2287     1  0   Mar 31 ?        0:00 ora_s000_hysms02  oracle  2275     1  0   Mar 31 ?        0:04 ora_reco_hysms02  oracle 21023 21012  0 18:52:59 pts/65   0:00 grep ora_

DBWR的进程号是2266。
使用Top命令观察一下:

oracle:/oracle/oracle8>toplast pid: 21145;  load averages:  3.38,  3.45,  3.67               18:53:38725 processes: 711 sleeping, 1 running, 10 zombie, 3 on cpuCPU states: 35.2% idle, 40.1% user,  9.4% kernel, 15.4% iowait,  0.0% swapMemory: 3072M real, 286M free, 3120M swap in use, 1146M swap free   PID USERNAME THR PRI NICE  SIZE   RES STATE    TIME    CPU COMMAND 11855 smspf      1  59    0 1355M 1321M cpu/0   19:32 16.52% oracle  2264 oracle     1   0    0 1358M 1316M run    283.3H 16.36% oracle 11280 oracle     1  13    0 1356M 1321M sleep   79.8H  0.77% oracle  6957 smspf     15  29   10   63M   14M sleep  107.7H  0.76% java 17393 smspf      1  30    0 1356M 1322M cpu/1  833:05  0.58% oracle 29299 smspf      5  58    0 8688K 5088K sleep   18.5H  0.38% fee_ftp_get 21043 oracle     1  43    0 3264K 2056K cpu/9    0:01  0.31% top 20919 smspf     17  29   10   63M   17M sleep  247:02  0.29% java 25124 smspf      1  58    0   16M 4688K sleep    0:35  0.25% smif_status_rec  8086 smspf      5  23    0   21M   13M sleep   41.1H  0.24% fee_file_in 16009 root       1  35    0 4920K 3160K sleep    0:03  0.21% sshd2 25126 smspf      1  58    0 1355M 1321M sleep    0:26  0.20% oracle  2266 oracle     1  60    0 1357M 1317M sleep  811:42  0.18% oracle 11628 smspf      7  59    0 3440K 2088K sleep    0:39  0.16% sgip_client_ltz 26257 smspf     82  59    0  447M  178M sleep  533:04  0.15% java

我们注意到，2266号进程消耗的CPU不过0.18%,显然并不繁忙,那么瓶颈就很可能在IO上。
使用IOSTAT工具检查IO状况。

gqgai:/home/gqgai>iostat -xn 3                    extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device......    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t6d0    1.8   38.4   32.4  281.0  0.0  0.7    0.0   16.4   0  29 c0t10d0    1.8   38.4   32.4  281.0  0.0  0.5    0.0   13.5   0  27 c0t11d0   24.8   61.3 1432.4  880.1  0.0  0.5    0.0    5.4   0  26 c1t1d0    0.0    0.0    0.0    0.0  0.0  0.0    0.0    9.1   0   0 hurraysms02:vold(pid238)                    extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device........    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t6d0    0.3    8.3    0.3   47.0  0.0  0.1    0.0    9.2   0   8 c0t10d0    0.0    8.3    0.0   47.0  0.0  0.1    0.0    8.0   0   7 c0t11d0   11.7   65.3  197.2  522.2  0.0  1.6    0.0   20.5   0 100 c1t1d0    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 hurraysms02:vold(pid238)                    extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device........    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t6d0    0.3   13.7    2.7   68.2  0.0  0.2    0.0   10.9   0  12 c0t10d0    0.0   13.7    0.0   68.2  0.0  0.1    0.0    9.6   0  11 c0t11d0   11.3   65.3   90.7  522.7  0.0  1.5    0.0   19.5   0  99 c1t1d0    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 hurraysms02:vold(pid238)                    extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device........    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t6d0    0.0    8.0    0.0   42.7  0.0  0.1    0.0    9.3   0   7 c0t10d0    0.0    8.0    0.0   42.7  0.0  0.1    0.0    9.1   0   7 c0t11d0   11.0   65.7  978.7  525.3  0.0  1.4    0.0   17.7   0  99 c1t1d0    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 hurraysms02:vold(pid238)                    extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device........    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 c0t6d0    0.3   87.7    2.7  433.7  0.0  2.2    0.0   24.9   0  90 c0t10d0    0.0   88.3    0.0  436.5  0.0  1.8    0.0   19.9   0  81 c0t11d0   89.0   54.0  725.4  432.0  0.0  2.1    0.0   14.8   0 100 c1t1d0    0.0    0.0    0.0    0.0  0.0  0.0    0.0    0.0   0   0 hurraysms02:vold(pid238)

我们注意到，存放数据库的主要卷c1t1d0的繁忙程度始终处于99~100,而写速度却只有500K/s左右，这个速度是极为缓慢的。
(%b percent of time the disk is busy (transactions in progress)
Kw/s kilobytes written per second)
根据我们的常识T3盘阵通常按Char写速度可以达到10M/s左右，以前测试过一些Tpcc指标，可以参考:Use bonnie to Test system IO speed。
而正常情况下的数据库随机写通常都在1~2M左右，显然此时的磁盘已经处于不正常状态，经过确认的确是硬盘发生了损坏，Raid5的Group中损坏了一块硬盘。
经过更换以后系统逐渐恢复正常。

Posted by eygle at June 26, 2005

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